Why aren't people working on thorium reactors? Wikipedia lists current projects in the US (~2015), India (~2013) and China (~?). The reason for India's intere

Why aren't people working on thorium reactors? Wikipedia lists current projects in the US (~2015), India (~2013) and China (~?). The reason for India's interest in the technology should be obvious, and it's quite probable that we'll see further development on that front.